The field of the invention is in the art of firearms and more particularly in the art of adapters to provide for the firing of conventional low power ammunition in a gun originally designed for higher power cartridges.
The economic and psychological advantages of training, practicing, and the taking of small game with low power ammunition in a gun conventionally designed for higher power ammunition is well recognized. Adapter "cartridges", sometimes called auxilliary cartridges, for containing the low power round and fitting the chamber of the high power gun have been known since before the turn of the century. A conversion adapter for the Government model .45 caliber ACP converting it to fire .22 caliber rimfire cartridges has been available since prior to World War II. That conversion required a new barrel since the calibers of the bullets were different. The invention disclosed herein does not require any change of barrels since the bullet diameters of the original high power cartridge and the conversion low power cartridge are substantially the same.
Typical examples of modern prior art devices are exemplified by U.S. Pat. No. 3,771,415 to patentees Into and Costello, and U.S. Pat. No. 3,776,095 to patentee Atchisson. A review entitled "AR-15 Rimfire Conversion", by the Technical Staff of the National Rifle Association appearing in the American Rifleman for May 1973 commencing at page 63, is pertinent and informative of problems in the prior art devices.